I as well didn't found much differences between the dry and pre-soak methods. However, if you are running processes at higher temperatures, a pre-soak is the more effective way to pre-heeat film and tank.

There are some exotic film/developer combinations that need or must not have a pre-soak, but generally it does not have a significant effect.

@Ed,
since the Amaloco C-41 Process recommends a pre-soak, I accidentially developed some films with the Tetenal C-41 Process with pre-soak, too (my ATL was programmed that way). If worked very well. I have not seen any differences/problems and thus didn't change the programm.